Help with Unknown Predator

[Whatigot]

adversely, the brown shrimp you saw could have been a mantis shrimp which are quite agressive as well.
I have seen my pistols snap at passing fish and had a problem losing fish until I started to feed the tank a little extra to make sure all appettites were satiated.
If you feed your tank a frozen mix for carnivores right after lights out (or even better, wait until it's midnight on your light cycle) you will most likely see your predator at least poke his head out to see what the smell is all about.

Good luck, and people will try and tell you that pistols won't harm fish, but the kind that I got from King Eds on their Cuban LR are not your typical tiger or alpheidae as they don't care about my shrimp gobie and will viciously attack anything that gets too close to their home (which is a hole in LR).

As of yet I haven't actually seen a fish die from one of their attacks (though I HAVE seen attacks), but I buy bigger fish now after I was consistently losing smaller ones in addition to simply feeding the tank a little more.

Look up a bottle trap in the DIY section and you should have some success catching or iding your predator with a little patience.

[Green Phantom]

There is something definitely killing off my fish. I saw the other injured sleeper goby had died this morning.

Thank you everyone for your help and input. I'm going to try the bottle trap tonight.